If this is the first time you have done this, then your own
actual labor time should be maybe around two hours. It could
be a lot less if you are handy with cools and removing
interference on your car to get to the actual thermostat.

Diagrams like
http://media.honda.co.uk/car/owner/media/manuals/CivicManual/pdf/10-7.pdf
and the exploded parts diagram at bkhondaparts.com may be
helpful.

You want to have a new thermostat gasket; use only an OEM
thermostat; and have extra coolant (Honda OEM or whatever
you have been using). You should purge the system of air
afterwards, or at least top off the radiator and monitor the
reservoir level (adding coolant as needed) for a week or so
afterward.

I would not expect new bolts to be necessary.